Hi Andrey,
Sorry but I did not get well what kind of experiment I should make.
My statement regarding the mag guiding is that once you have tuned well the wire and the mag dimension and gap between the wire and the mag, the arm wand react as follow:
1) The mag in default keep centred the wire track, but also allow the micro movements due to the eccentricity fo the record in plus or minus with the tendency to return to center when the record turn centred.
I do not understand well ( sorry for my slow understanding of things ) how a side rigid contact cam allow the plus and minus off centred of the record can keep the cam in contact with the bearing. In my mind should loose contact depending on the off centred of the record, being not a fixed swing system but a side contact. May be I am wrong and if so I have no problem to accept.
Regarding the inner position of the cam comparing to the original LT TA I also could not imagine the advantage therefore I asked.
Thank you and best regards
Adelmo
Sorry but I did not get well what kind of experiment I should make.
My statement regarding the mag guiding is that once you have tuned well the wire and the mag dimension and gap between the wire and the mag, the arm wand react as follow:
1) The mag in default keep centred the wire track, but also allow the micro movements due to the eccentricity fo the record in plus or minus with the tendency to return to center when the record turn centred.
I do not understand well ( sorry for my slow understanding of things ) how a side rigid contact cam allow the plus and minus off centred of the record can keep the cam in contact with the bearing. In my mind should loose contact depending on the off centred of the record, being not a fixed swing system but a side contact. May be I am wrong and if so I have no problem to accept.
Regarding the inner position of the cam comparing to the original LT TA I also could not imagine the advantage therefore I asked.
Thank you and best regards
Adelmo
Now the answer is up to you and Carlo. The ball is in your court.
No thanks - not mine
In the past i've done a couple of Birch geometry tangentials, the belted Rabbit and the Doug's dual pivot 3DToy, but I've always stayed away from "cam driven".
First because their official geometry is a trade secret, and i dont' know how to design it correctly; second because I'm not convinced by the cams: the magnetic ones because I still remember of Earnshaw, and the rigid ones because they are rigid and can bring problems on warps and eccentrics.
My congratulation, Andrey, are deserved to a novelty (rare, nowadays) in this typology: i like new things, and I'm already happy if are not worse than the old ones.
c
No thanks - not mine
In the past i've done a couple of Birch geometry tangentials, the belted Rabbit and the Doug's dual pivot 3DToy, but I've always stayed away from "cam driven".
First because their official geometry is a trade secret, and i dont' know how to design it correctly; second because I'm not convinced by the cams: the magnetic ones because I still remember of Earnshaw, and the rigid ones because they are rigid and can bring problems on warps and eccentrics.
My congratulation, Andrey, are deserved to a novelty (rare, nowadays) in this typology: i like new things, and I'm already happy if are not worse than the old ones.
c
Well then.
I won't insist.
I had a strange feeling, Carlo, after reading your post.
I really wanted to know what mechanisms with a cam left such terrible memories of cam drives in your memory? Tell me.
I read in this thread about concerns about the safety of the cartridge when using a cam.
However, my experiments disproved these concerns.
When playing records with defects, the needle holds the groove much better with Aki Schroeder than with a conventional tonearm.
Eccentricity is worked out easily and naturally, the needle displacement is not visible to the eye.
To test the tonearm operation with eccentricity, I prepared a record with adjustable eccentricity (in the photo).
I tested it up to 4 mm.
The tonearm arm described complex movements to the right-left and back-and-forth.
In this case, the bearing was pressed tightly against the surface of the guide when moving in all directions, without coming off the guide.
This indicates that during the return stroke of the eccentricity, the tonearm shifts back,thereby maintaining the correct tangential position of the needle.
Watch the video in my first post again, perhaps you did not watch it carefully.
I do not make any commercial secrets out of the cam geometry.
Yes, and explain what Earnshaw is and how it is connected with your memories.
AG.
I won't insist.
I had a strange feeling, Carlo, after reading your post.
I really wanted to know what mechanisms with a cam left such terrible memories of cam drives in your memory? Tell me.
I read in this thread about concerns about the safety of the cartridge when using a cam.
However, my experiments disproved these concerns.
When playing records with defects, the needle holds the groove much better with Aki Schroeder than with a conventional tonearm.
Eccentricity is worked out easily and naturally, the needle displacement is not visible to the eye.
To test the tonearm operation with eccentricity, I prepared a record with adjustable eccentricity (in the photo).
I tested it up to 4 mm.
The tonearm arm described complex movements to the right-left and back-and-forth.
In this case, the bearing was pressed tightly against the surface of the guide when moving in all directions, without coming off the guide.
This indicates that during the return stroke of the eccentricity, the tonearm shifts back,thereby maintaining the correct tangential position of the needle.
Watch the video in my first post again, perhaps you did not watch it carefully.
I do not make any commercial secrets out of the cam geometry.
Yes, and explain what Earnshaw is and how it is connected with your memories.
AG.
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...terrible memories of cam drives in your memory?
No one. simply because i've never used.
And the trivial reason (after the mistery geometry) is that if the Tangential TAs were born using pivots to avoid the Linear sliding cart issues, seems strange for me to introduce a sliding device in a PTTA.
Eccentric test - RIAA standard is less < 1mm - so 1,5 is more than enough to test: we are dealing with bendings <<< 01mm, visible just with a macroscope. It's a test conceived for Linears, never seen pivoted o PTTA facing problems with. I mean decent ones, of course
c
Earnshaw theorem- better wikipedia than me for sure
No one. simply because i've never used.
And the trivial reason (after the mistery geometry) is that if the Tangential TAs were born using pivots to avoid the Linear sliding cart issues, seems strange for me to introduce a sliding device in a PTTA.
Eccentric test - RIAA standard is less < 1mm - so 1,5 is more than enough to test: we are dealing with bendings <<< 01mm, visible just with a macroscope. It's a test conceived for Linears, never seen pivoted o PTTA facing problems with. I mean decent ones, of course
c
Earnshaw theorem- better wikipedia than me for sure
Hi Andrey,
Tks for your comment, here below is my opinion:
I did not say that the cam guide with bearing contact do not keep, overall, the tangent 90 degree tracking.
1) I said that the LP eccentricity make micro movements in the bearing contact point ( plus or minus depending on the LP eccentricity and geometry/length of the wand and the brackets ) and since there is a fixed side contact line/point it provides, depending on the level of eccentricity, a kind of pressing or detaching of the contact between the side cam and the bearing. The pressing some where need to be discharged, I suppose it shall into the cart area increasing or decreasing also the bias force in one side or the other. This is not matter we can see or not in the video, but I am strongly convinced that it happens and that is there anyhow.
2) Sound wise does it matter or not, for the safety of the cart in the long term use does it matter or not?. Well, I do not know and generally speaking I avoid to comment the sound of our systems or diy TAs.
3) Is it better a side cam VS a mag cam? I have no idea though I am currently using since many month on regular basis in my LT TA clone a mag cam and I am happy with it.
By the way I am not planning to change any other guy opinion as I believe, if we are happy with our diy, that is all it matters.
Best regards
Adelmo
Tks for your comment, here below is my opinion:
I did not say that the cam guide with bearing contact do not keep, overall, the tangent 90 degree tracking.
1) I said that the LP eccentricity make micro movements in the bearing contact point ( plus or minus depending on the LP eccentricity and geometry/length of the wand and the brackets ) and since there is a fixed side contact line/point it provides, depending on the level of eccentricity, a kind of pressing or detaching of the contact between the side cam and the bearing. The pressing some where need to be discharged, I suppose it shall into the cart area increasing or decreasing also the bias force in one side or the other. This is not matter we can see or not in the video, but I am strongly convinced that it happens and that is there anyhow.
2) Sound wise does it matter or not, for the safety of the cart in the long term use does it matter or not?. Well, I do not know and generally speaking I avoid to comment the sound of our systems or diy TAs.
3) Is it better a side cam VS a mag cam? I have no idea though I am currently using since many month on regular basis in my LT TA clone a mag cam and I am happy with it.
By the way I am not planning to change any other guy opinion as I believe, if we are happy with our diy, that is all it matters.
Best regards
Adelmo
I am a practitioner, not a theorist. I make my toys that appear in my head,and only then try to explain the results obtained.
And not the other way around.
The knowledge I have long ago acquired and my natural intuition allow me to avoid big mistakes, and no one is immune from small mistakes.
"RIAA standard is less than <1 mm".
This is for record manufacturers. We call it GOST - state standard.
I prefer to conduct tests in extreme conditions, then you won't need a macroscope.
I carefully observed the bearing movement at different eccentricities both with and without a macroscope.
I did not detect any separation from the cam surface.
From this I concluded that the bearing exactly follows the cam trajectory - which was required to be proven.
I would be extremely curious to see the movement of the magnet relative to the cam of the Schroeder LT tonearm.
That's why I suggested to Adelmo to conduct a joint experiment.
If he still dares and makes the same record as I showed in the photo, then he will be able to show us a video of the movement of the tonearm and magnet along the guide at an eccentricity of 3 mm, as in my video.
I, like you, do not like all these lever mechanisms with cams and they are not currently in the circle of my interests.
In the fall, I will continue my studies on my new concept, and if the outcome is positive, I will be able to show some designs.
And now I have a restI am closely following the development of your idea in the topic of linear tonearms.
I confirm - this is a brilliant idea and it has a solution.
It would be interesting to know your system of grading devices by decency.
If you would be so kind.
AG.
I completely agree with you.
I am also against agitation for some technical solution.
Everyone decides for themselves.
But we are DIYers and we are not held back by any commercial interest.
It is the tonearm manufacturers who can talk for hours about insignificant achievements,which can hardly be called achievements, while importantly and widely puffing out their cheeks.
And keeping silent about the shortcomings.
I do not blame them, in their place I would do the same.
But we, DIYers, can directly ask uncomfortable technical questions andlook for their solutions.
Precisely technical questions, without any personal preferences.
With great respect for your determination,
AG.